Biofunctional photoluminescent nanocomplexes for visualisation of intracellular molecular trafficking, diagnostics and therapy
At the same time, the nanoparticle surface can host biofunctional surface moieties, enabling attachment of targeting and/or therpeutic cargo molecules.
These nanoparticle biocomplexes, such as FND-EGFP, nanoruby-(opioid ligand) or UCNP-(designed ankyrin repeat antibodies) are pieced together to form biohybrid nanocomplexes capable to enter cells or pathology lesions to enable diagnosis and therapy.
Development of new approaches for the diagnosis and therapy of tumours (taken together, termed theranostics) - one of the most dynamic areas of Biomedicine, where new nanomaterials afford new opportunities. The nanomaterial merits include: programmability of their physical and chemical properties; abundance of reactive functional groups on the surface; large effective surface area; optimum size, which determines preferential accumulation of nanoparticles in tumour tissue1. This paper reports on multifunctional theranostics agents based on a new-generation biofunctional photoluminescent nanoparticles with unique optical properties – fluorescent nanodiamonds2, nanorubies3 and upconversion nanoparticles4.
UCNPs in the form of hexagonal crystallites NaYF4 doped with Yb3+ and Er3+ or Tm3+ were synthesised in the size range of 20 – 100 nm by a modified solvothermal method 5 [see Fig. 1(a,b)]. Nanorubies mean-sized 30 nm were produced by a femtosecond laser ablation method and high-energy ball milling, allowing the gram-scale, low-cost production3. Initially hydrophobic UCNPs were hydrophilised and coated with polymer or silica (Figure 1) 6. Surface-functionalised nanorubies appeared amenable to silane-based tethering of opioid receptor antibodies (Fig 2), such as designed ankyrin repeat proteins (DARPin)7 and mini-antibodies. We demonstrated binding of functional proteins by flexible design using solid surface peptide binding technology 6. The attachment of therapeutic vectors for photodynamic therapy, such as Rose Bengal6 and Killer Red, and immunotherapy, such as Exotoxin 7, were also developed and demonstrated.
Figure 1. (Top panel) TEM images of upconversion nanoparticles (UCNP). (c) Core-shell UCNPs coated with silica and loaded coatings and loaded with photosenstiser Rose Bengal (RB); Inset, UCNP@SiO2(RB) pelleted (left) and dispersed (right) in water.
Figure 2. Microscopy images of AtT-20 cells incubated with nanorubies. (Top panel), (Middle panel) and (Bottom panel) show bright field, epi-luminescence and time-gated, background-free images. Insets show zoomed-in images as framed by blue squares. A red circle marks the nanoruby indiscernible in Middle panel. Scale bars, 10 μm.
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(5) Zhao, J. B.; Jin, D. Y.; Schartner, E. P.; Lu, Y. Q.; Liu, Y. J.; Zvyagin, A. V.; Zhang, L. X.; Dawes, J. M.; Xi, P.; Piper, J. A.; Goldys, E. M.; Monro, T. M. Nature Nanotechnology 2013, 8, 729.
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